Wednesday, April 6, 2016

Levenea subcarinata pumilis brachiopod from the Bois d'Arc formation of Oklahoma

One of the more common brachiopods that I found in the Bois d'Arc formation is Levenea subcarinata pumilis. It is similar to Rhipimelloides oblata except for a few key features. The hinge line is wide and straight and the presence of a wide, shallow fold/sulcus structure. Otherwise they share some similar traits like the rounded shape to the shell and the  pedicle valve extending slightly past the brachial valve. Another difference are the fine costae on the valve surfaces which on L. subcarinata pumilis are more curved instead of straight. the margin between the valves is flat except for where it bends to follow the fold/sulcus.

Specimen #1 - Brachial valve
Anterior
Pedicle valve
Posterior
Profile

Specimen #2 - Brachial valve
Anterior
Pedicle valve
Posterior
Profile

The specimens I found in the Bois d'Arc formation are larger than those that I have from the Haragan formation. This is also noted by Amsden and he attributed this to clearer waters with less sediment in the Bois d'Arc.

I found the specimen shown on this page in the Bois d'Arc formation (Cravatt member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc and Haragan formations interfinger with each other and are roughly the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

References:
"Stratigraphy and Paleontology of the Hunton Group in the Arbuckle Mountain Region, Part V - Bois d'Arc Articulate Brachiopods " Amsden, 1958, Oklahoma Geological Survey Bulletin 82

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